title: Proposal and validation of a quick question to rate the influence of sun exposure in geriatric epidemiological studies on vitamin D.
abstract: BACKGROUND
  Vitamin D is synthesized in the skin under the action of solar ultraviolet-B radiation. The objective of this study was to determine whether a simple question exploring sun exposure ("When weather is nice, do you stay more than 15 minutes exposed to the sun (face and hands uncovered) between 11am and 3pm?") could be associated with serum 25-hydroxyvitamin D status among 751 older community-dwelling women (mean age, 80.2 ± 3.5 years).
  
  
  METHODS
  Two groups were distinguished based on the binary "Yes" versus "No" answer. Hypovitaminosis D was defined as serum 25-hydroxyvitamin D < 30 ng/mL.
  
  
  RESULTS
  Fewer women with hypovitaminosis D answered "Yes" to the question on sun exposure (p = 0.042). Answering "Yes" was inversely associated with hypovitaminosis D (OR = 0.56, p = 0.049) after adjustment for demographic characteristics and exogenous sources of vitamin D, with a positive predictive value of 88 %.
  
  
  CONCLUSIONS
  This simple question may reflect the sun's influence on vitamin D status and identify older community-dwellers with hypovitaminosis D.
authors.affiliation: Department of Neuroscience, Division of Geriatric Medicine, Angers University Hospital, Angers University Memory Clinic, UNAM, Angers, France. CeAnnweiler@chu-angers.fr
authors.forename: Cédric
authors.initials: C
authors.lastname: Annweiler
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Schott
authors.forename: Olivier
authors.initials: O
authors.lastname: Beauchet
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D013472:Sunlight; D014807:Vitamin D / Q000031:analogs & derivatives / Q000096:biosynthesis / Q000097:blood; D014808:Vitamin D Deficiency / Q000517:prevention & control*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D